Project Summary Despite the success of antiretroviral therapy (ART), individuals infected with Human Immunodeficiency Virus (HIV) still have a greater mortality than those who are uninfected, mostly due to death from inflammation- related non-communicable diseases (NCDs), such as cardiovascular disease (CVD) and kidney dysfunction. The drivers of this chronic immune activation and associated CVD remain largely unknown. Recent studies have shown that HIV infection results in disruptions in the gut microbial community and these alterations are associated with gut barrier dysfunction, bacterial translocation, and systemic immune activation. However, published studies have primarily examined populations in the developed world, even though the greatest burden of HIV-infection and associated CVD exists in the developing world. We remain the only group to report on HIV-associated changes in the gut microbiome in populations living in sub-Saharan Africa. Our published studies and preliminary data indicate that there are clear shifts in the gut microbiome, both bacterial and viral, with HIV-infection and that these correspond to increased measures of systemic inflammation. Independent of HIV, changes in the gut microbial community have been shown to produce inflammatory metabolites that cause macrophage and platelet activation, thrombosis, and arterial plaque formation. We propose to study HIV-associated gut microbial changes in two sub-Saharan African populations and measure systemic immune activation and cardiovascular outcomes associated with these changes. These studies will identify microbial candidates that we will then use in in vitro and in vivo models to investigate the causative relationship between HIV-associated gut microbial community changes and CVD. We will expose gut and vascular cells to HIV- associated microbes of interest and measure the inflammatory response to these organisms. We will also use an established murine model of atherosclerosis to transplant candidate microbes and/or stool communities into animals to characterize the development of CVD induced by these microbes. The specific aims of this project are to: 1) Determine the associations between changes in enteric microbial communities, increased immune activation, and cardiovascular disease in HIV-infected individuals in sub-Saharan Africa and 2) Utilize both in vitro and in vivo models to assess mechanisms by which HIV-associated enteric microbial communities promote chronic inflammation and cardiovascular disease. The goal of the proposed work is to identify specific mechanisms by which HIV-associated alterations in the gut microbiome (including bacteria, viruses, fungi and parasites) contribute to CVD pathogenesis in chronic HIV infection and help inform the development of new therapeutic interventions that leverage the gut microbiome to extend lifespan and improve quality of life for HIV-infected individuals.